SUBLETHAL TOXIC EFFECTS OF ALUMINUM ON THE EARTHWORM EISENIA-FETIDA

Aluminium is the third most abundant element in the Earth's crust but because of the low solubility of its silicates, phosphates and oxides it has. until recently, been considered to be excluded from biochemica l and metabolic processes. However, the toxicity of soluble aluminium to plants, fish and other animal groups is now well documented. Little data are available on the interaction of aluminium with earthworms an d this study is a laboratory investigation designed to test the sublet hal effects of aluminium, at three pi-Is (4.0, 5.5, 6.5), on the earth worm species Eisenia fetida grown in artificial soil. Several conclusi ons were reached: (a) the lethal dose at pH 4.2 is between 2000 and 40 00 mg kg(-1); (b) high levels of aluminium inhibit cocoon production b etween pH 4 and pH 7; (c) intermediate levels of aluminium stimulate c ocoon production at pH 6-7; (d) low levels of aluminium inhibit hatchi ng and juvenile production at low pH and (e) cocoon viability and juve nile production are stimulated by subjecting parents to intermediate l evels of aluminium at pH 6-7.